1. Field of the Invention
The present invention relates to the feeding of cylindrical components to a work station and more particularly to the feeding of axial lead electronic components, such as resistors, diodes and capacitors.
Many types of manufacturing operations require the transmission of individual cylindrical components to an assembly station for automatic or manual incorporation of the component into a product or subassembly. In particular, the manufacture of electronic products frequently utilizes large numbers of axial lead electronic components. These components are often obtained in bulk, and must be dispensed serially in a manner permitting their utilization in such operations as automatic or manual insertion into circuit boards.
2. Description of the Prior Art
A common method of serializing axial lead components from a bulk stock is to employ a vibrating bowl. Bulk components are fed into the bowl, and vibrations of the bowl, in conjuncton with the force of gravity, cause components to align with an exit of the bowl. Parts leaving the bowl enter a vertically disposed track. The longitudinal interior cross-section of the track is just slightly larger than the body of the axial lead component, thus maintaining components within the track in a serialized, single-file disposition. Longitudinal slots run the full length of two parallel sides of the track. The slots are wide enough to permit the component leads to protrude through the slot, yet small enough to prevent the body of the component from protruding through the slot.
The parts-carrying tracks often have a zig-zag, or saw-toothed slot disposition, rather than being straight tracks. The zig-zag path slows the vertical descent rate of the part to a desired value less than what would be achieved by free-fall of the parts. Furthermore, parts queing which occurs at saw-toothed vertices tends to bring parts within the track into an adjacent, parallel configuration, with bodies of the parts essentially horizontal.
Parts that have once entered the zig-zag track from a vibratory bowl feeder usually travel without difficulty. However, vibratory bowl feeders are frequently plagued by jams occurring within the bowl and at the bowl exit. Also, the susceptibility to jamming of vibratory bowl feeders is aggravated by even slight bends in the component leads.
In addition to vibratory bowl feeders, feeders which employ magnetic fields have been developed. One obvious disadvantage of magnetic field feeders is the limitation of the usage to components having magnetic leads.
A system which does not use either a vibratory bowl feeder or magnetic fields is disclosed in U.S. Pat. No. 4,171,051 to Wullenwaber, the same inventor as in the present application. In the system disclosed in this patent, bulk components are fed to a "feeder-serializer" which produces a single-file progression of components. Three chambers are defined in the serializer by means of blocking gates which are movable into and out of the path of components moving through the serializer. By defining an upper entrance chamber, an intermediate storage chamber and a lower exit chamber, and properly controlling the operation of the gates, the number of components in the lower exit chamber is limited and jamming at the exit is prevented. Although this apparatus has distinct advantages over vibratory bowl feeders, it is also susceptible to jamming problems as a result of the operation of the gates which move in and out of the path of the components.